US20120131877A1

Movatterモバイル変換

Info

Publication number: US20120131877A1
Application number: US13/334,510
Authority: US
Inventors: Biao Fang; Huageng Luo
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2011-12-22
Filing date: 2011-12-22
Publication date: 2012-05-31
Anticipated expiration: 2031-12-22
Also published as: US8393118B2

Abstract

A wind turbine lattice tower structure includes a plurality of structural members connected together to define an open lattice tower, with the structural members including vertical leg members and diagonal braces extending between the vertical leg members. Pairs of the diagonal braces form cross braces having an intersection point therebetween. A damping bolt connection assembly is provides at the intersection point of the cross braces and is configured to attach the cross braces together at the intersection point while providing for relative movement of each individual cross brace along a defined longitudinal section of the other respective cross brace.

Description

FIELD OF THE INVENTION

The present invention relates generally to wind turbine tower structures, and more particularly to an improved bolt connection for lattice tower structures.

BACKGROUND OF THE INVENTION

Conventional wind turbine towers typically include a tubular pole or a lattice structure to support a wind turbine at a considerable height to capture wind energy. The tubular pole configuration is relatively more simple and easier to assemble than the lattice structure. However, tubular poles use more steel than the lattice structure, resulting in a cost disadvantage with rising prices of steel.

The lattice structure towers use significantly less steel and other materials as compared to conventional tubular towers (generally about 30%-40% less). The lattice towers, however, lack the torsional rigidity of the tubular constructions and this decreased torsional stiffness potentially induces vibrations and stresses in the tower that must be compensated for.

It is known in the civil engineering and construction arts to incorporate damping devices and materials in structures to reduce vibrations, harmonics, and the like. An effective and practical means of damping lattice frame wind towers, however, has not been achieved. In fact, the conventional practice of rigid connections (e.g. bolt or weld connections) at the numerous joints between the vertical structural elements (“legs”) and the cross braces that extend between the legs, as well as at the intersection of the cross braces, may even exacerbate the vibrations and resulting stresses. Vibrations caused by wind against the wind turbine tower may even loosen bolted connections over time.

Accordingly, an improved means for providing effective and practical damping to a lattice frame wind tower, without detracting from the inherent benefits of the structure as compared to tubular towers, is desired.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In accordance with aspects of the invention, a wind turbine lattice tower structure includes a plurality of structural members connected together to define an open lattice tower. The structural members include, for example, vertical leg members and diagonal braces extending between the vertical leg members. Pairs of the diagonal braces form cross braces that cross at an intersection point. A damping bolt connection assembly is operably disposed at the intersection point of the cross braces and is configured to attach the cross braces together at the intersection point while providing for relative movement of each individual cross brace along a defined longitudinal section of the other respective cross brace.

In a particular embodiment, the damping bolt connection assembly includes a longitudinally elongated slot defined in each of the cross braces, with the slots overlying at the intersection point. A pin component having a shaft, such as a threaded bolt and nut, extends through the slots and connects the cross braces together at the intersection point. In this manner, the elongated slots define the range of relative movement of each of cross brace relative to the other cross brace.

It certain embodiments, a friction disk is disposed between facing surface of the cross braces at the intersection point. The friction disk is formed from a friction-enhancing material that increases the friction of the relative sliding movement between the facing surfaces of the cross braces, thus adding additional vibration damping into the system.

In some embodiments, a spring mechanism may be configured on the shaft to exert a constant clamping force between the pin and the cross braces, for example in situations when vibrations would tend to loosen a threaded bolt connection at the intersection point. In this arrangement, the pin component includes a head (such as the head of a bolt, and the spring mechanism includes a mechanical spring disposed concentric with the shaft between the head and the proximal cross brace to urge the head axially away from the cross braces. The mechanical spring may be any manner of spring, such as a leaf spring, coiled spring, spring washer, and so forth.

In other embodiments the spring mechanism may include a cylindrical elastomeric material member, such as a rubber or rubber-like cylinder, disposed concentric with the shaft between the head and proximal cross braces to urge the head axially away from the cross braces. The pin component may be a threaded bolt that is secured to the cross braces with a nut, with the bolt tightened against the opposed biasing force of the elastomeric material member. The elastomeric material member may be restrained in a rigid outer circumferential sleeve.

In one embodiment, the cross braces have longitudinal ends that are non-rotationally fixed to the vertical leg members. For example, a plurality of bolts, rivets, or other connectors may be used at the attachment point of the longitudinal ends to prevent rotational movement of the ends relative to the vertical leg members.

In another embodiment, increased movement and flexibility between the cross braces and vertical leg members may be desired, and the longitudinal ends of the cross braces are rotationally fixed to the vertical leg members. For example, a single bolt, rivet, or the like may be used to attach the members and may define a pivot point for relative (limited) rotational motion between the cross brace and vertical leg member.

It should be appreciated that the present invention encompasses any manner of wind turbine lattice tower structure having any combination of the various features and characteristics set forth above and discussed in greater detail below.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 is a perspective view of a wind turbine with a lattice tower structure;

FIG. 2 is a perspective view of an alternative embodiment of a wind turbine with a lattice tower structure;

FIG. 3 is a detailed perspective view of structural components of a wind turbine lattice tower structure particularly illustrating a damping bolt connection assembly at the intersection of a pair of cross braces;

FIG. 4 is a schematic view of an embodiment of a damping bolt connection at the intersection of a pair of cross braces;

FIG. 5 is a schematic view of an alternative embodiment of a damping bolt connection at the intersection of a pair of cross braces;

FIG. 6 is a partial perspective view of an embodiment of a damping bolt connection;

FIG. 7 is an in-line component view of an embodiment of a damping bolt connection; and

FIG. 8 is an in-line component view of an alternative embodiment of a damping bolt connection.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

FIGS. 1 and 2 are perspective views ofexemplary wind turbines10. Eachwind turbine10 includes a plurality ofblades12 mounted to arotor hub14, which in turn is rotationally supported any manner of power generation components housed within anacelle16, as is well known in the art. Thenacelle16 is supported atop atower structure18, which in the illustrated embodiments is an open lattice structure formed by vertically orientedlegs22,horizontal braces26, anddiagonal braces24.

Thelegs22 are typically angle iron members or pipe members, and the

braces

24,26 are typically angle iron members. These latticeframe tower structures18 are also referred to in the art as “space frame” towers. Thelattice tower structure18 may be fabricated in sections and erected at the wind turbine site.

In the embodiment ofFIG. 1, acladding material28 is applied over the lattice structure, which may be any type of suitable fabric, such as an architectural fabric designed for harsh weather conditions. Thecladding28 protects workers and equipment within the tower and provides an aesthetic appearance to thewind turbine10.

FIG. 3 is a more detailed view of components of thelattice structure tower18, and particularly illustrates the connection locations between the

braces

24,26 and thelegs22. The diagonal braces24 extend betweenvertical legs22, and certain pairs of thesediagonal braces24 form pairs of cross braces that cross at anintersection point30. A vibration/oscillation dampingbolt connection assembly32 is utilized at theintersection point30 of the cross braces24 to physically attach thebraces24 together yet, at the same time, allow or a defined degree of longitudinal movement of the respective cross braces relative to each other. Any one or combination of thecross braces24 within thetower structure18 may incorporate the dampingbolt connection assembly32, and it should be appreciated that not every pair of cross braces within thetower structure18 need have the dampingbolt connection assembly32. The combination of dampingbolt connection assemblies32 serve to diminish vibrations and “swaying” of thetower structure18 that are inherently produced by a combination of factors, such as wind speed and direction, load on the wind turbine, blade imbalances, and so forth. Embodiments of the dampingbolt connection32 are described in greater detail below.

Referring toFIGS. 4 through 8 in general, an embodiment of a dampingbolt connection assembly32 includeselongated slots34 defined in the cross braces24 such that theslots34 overly at theintersection point30. The longitudinal length of eachrespective slot34 defines the range of relative movement between the respective braces24. Apin component36 includes ahead38 and ashaft40 that extends through the overlyingslots34. In a particular embodiment, thepin component36 is a threadedbolt42 that is engaged by anut44. In other embodiments, thepin component36 may be, for example, a rivet, rod, or other like device. Thepin component36 serves to physically connect the cross braces24 together at theintersection point30 while allowing for relative movement of thebraces24.

Referring toFIGS. 7 and 8, a friction-enhancing member, such as afriction disk46, may be provided on theshaft40 between the facing surfaces of thebraces24. Thisdisk46 is formed of any manner of known friction-enhancing material and promotes increased sliding friction between thebraces24, thus further serving to dampen vibrations within the system.

Aspring mechanism48 may be incorporated with thepin component36 to apply a constant tensioning or clamping force to thebraces24 during relative movement of the braces or other structural members of thetower structure18, or loosening of thenut44 that may occur over time or due to structural vibrations. In the illustrated embodiments, the threadedbolt42 is tightened against the biasing force of thespring mechanism48 such that a constant axially directed tensioning force is generated along the bolt. Thespring mechanism48 may be variously configured. For example, in the embodiment ofFIG. 7, thespring mechanism48 may include amechanical spring50, such as a coiled or leaf spring. Themechanical spring50 may be encased in a housing orsleeve54 that is flanked bywashers60.

In the embodiment ofFIG. 8, thespring mechanism48 utilizes a cylindricalelastomeric material member52, such as a rubber or rubber-like cylinder, disposed concentric with theshaft40 between thehead38 and cross braces24 to urge thehead38 axially away from the cross braces. Theelastomeric material member52 may be restrained in a rigid outercircumferential sleeve54 such that compression of the material is restrained and directed axially along themember52. Thesleeve54 may be flanked bywashers60.

Referring toFIG. 5, in certain embodiments, the cross braces24 may have longitudinal ends that are non-rotationally fixed to thevertical leg members22, for example by a plurality ofbolts58, rivets, weld, or the like. In this embodiment, the cross braces are rigidly fixed to theirrespective leg members22 are do not move independently of the leg members.

In the embodiment ofFIG. 4, increased movement and flexibility between the cross braces24 andvertical leg members22 is achieved with a rotational connection between the longitudinal ends of the cross braces24 andvertical leg members22. For example, asingle bolt58, rivet, or the like may be used to attach thebraces24 to theleg members22 and define a pivot point for relative (limited) rotational motion between thecross brace24 andvertical leg member22.

It should be appreciated that the present invention encompasses any manner of wind turbinelattice tower structure18 having any combination of the various features and characteristics set forth above related to the dampingbolt connection assembly32.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A wind turbine lattice tower structure, comprising:

a plurality of structural members connected together to define an open lattice tower, said structural members including vertical leg members and diagonal braces extending between said vertical leg members;

pairs of said diagonal braces forming cross braces having an intersection point therebetween; and

a damping bolt connection assembly at said intersection point of said cross braces, said damping bolt connection assembly configured to attach said cross braces together at said intersection point while providing for relative movement of each individual cross brace along a defined longitudinal section of the other said respective cross brace.

2. The wind turbine lattice tower structure as inclaim 1, wherein said damping bolt connection assembly comprises longitudinally elongated and overlying slots defined in said cross braces at said intersection point, and a pin component having a shaft that extends through said slots and connects said cross braces together at said intersection point, wherein said elongated slots define the range of relative movement of one said cross brace relative to the other said cross brace.

3. The wind turbine lattice structure as inclaim 2, wherein said pin component and shaft comprise a threaded bolt that is secured to said cross braces with a nut.

4. The wind turbine lattice structure as inclaim 2, further comprising a friction disk disposed between facing surface of said cross braces at said intersection point, said friction disk formed from a material that enhances sliding friction between said facing surfaces of said cross braces.

5. The wind turbine lattice structure as inclaim 2, further comprising a spring mechanism configured on said shaft to exert a constant clamping force between said pin and said cross braces.

6. The wind turbine lattice structure as inclaim 5, wherein said pin component comprises a head, said spring mechanism comprises a mechanical spring disposed concentric with said shaft between said head and one of said cross braces to urge said head axially away from said cross braces.

7. The wind turbine lattice structure as inclaim 6, wherein said pin component comprises a threaded bolt that is secured to said cross braces with a nut, said bolt tightened against the opposed biasing force of said mechanical spring.

8. The wind turbine lattice structure as inclaim 5, wherein said pin component comprises a head, said spring mechanism comprising a cylindrical elastomeric material member disposed concentric with said shaft between said head and one of said cross braces to urge said head axially away from said cross braces.

9. The wind turbine lattice structure as inclaim 8, wherein said pin component comprises a threaded bolt that is secured to said cross braces with a nut, said bolt tightened against the opposed biasing force of said elastomeric material member.

10. The wind turbine lattice structure as inclaim 9, wherein said elastomeric material member further comprises a rigid outer circumferential sleeve.

11. The wind turbine lattice structure as inclaim 1, wherein said cross braces have longitudinal ends non-rotationally fixed to said vertical leg members.

12. The wind turbine lattice structure as inclaim 1, wherein said cross braces have longitudinal ends rotationally fixed to said vertical leg members.

13. The wind turbine lattice structure as inclaim 12, comprising a single pin connection between said longitudinal ends and said vertical leg members, wherein said cross braces may partially rotate relative to said vertical leg members via said pin connection.

14. A wind turbine lattice tower structure, comprising:

pairs of said diagonal braces forming cross braces having an intersection point therebetween;

a damping bolt connection assembly at said intersection point of said cross braces, said damping bolt connection assembly configured to attach said cross braces together at said intersection point while providing for relative movement of each individual cross brace along a defined longitudinal section of the other said respective cross brace;

said damping bolt connection assembly comprising longitudinally elongated and overlying slots defined in said cross braces at said intersection point, and a pin component having a shaft that extends through said slots and connects said cross braces together at said intersection point;

a friction disk disposed between facing surface of said cross braces at said intersection point, said friction disk formed from a material that enhances sliding friction between said facing surfaces of said cross braces; and

a spring mechanism configured on said shaft to exert a constant clamping force between said pin and said cross braces.

15. The wind turbine lattice structure as inclaim 14, wherein said pin component comprises a head, said spring mechanism comprising a mechanical spring disposed concentric with said shaft between said head and one of said cross braces to urge said head axially away from said cross braces.

16. The wind turbine lattice structure as inclaim 15, wherein said pin component comprises a threaded bolt that is secured to said cross braces with a nut, said bolt tightened against the opposed biasing force of said mechanical spring.

17. The wind turbine lattice structure as inclaim 14, wherein said pin component comprises a head, said spring mechanism comprising a cylindrical elastomeric material member disposed concentric with said shaft between said head and one of said cross braces to urge said head axially away from said cross braces.

18. The wind turbine lattice structure as inclaim 17, wherein said pin component comprises a threaded bolt that is secured to said cross braces with a nut, said bolt tightened against the opposed biasing force of said elastomeric material member.

19. The wind turbine lattice structure as inclaim 18, wherein said elastomeric material member further comprises a rigid outer circumferential sleeve.

20. The wind turbine lattice structure as inclaim 14, wherein said cross braces have longitudinal ends rotationally fixed to said vertical leg members.